To access MySQL from perl, you'll need to use the DBI package, a quick google search should provide plenty of examples for this.

http://www.google.ca/search?q=dbi+mysql+tutorial

I don't believe you can use PL/SQL, as it is proprietary to Oracle. I do remember there being a project to bring similar functionality to MySQL, though that was a couple years ago, and I can't seem to find any mention of it, recently.